Flocculation by chitosan was found to have superior technical and environmental performance among several algae harvesting technologies for N. oleoabundans. Alum was found to be ineffective as a flocculant for this alga, in contrast to reported results for other species, while the electricity use associated with filter press and centrifugation methods results in relatively high environmental impacts for these technologies. Despite the environmental preference of chitosan, alternate production routes could reduce the use of caustic soda, a chief source of current environmental burdens. These technical and environmental results complement economic analyses on the use of biopolymers in algae harvesting.